Catalyst for converting methanol and synthesis gas to ethanol

ABSTRACT

A process for selectively preparing ethanol by contacting methanol, hydrogen and carbon monoxide with a solid catalyst comprising rhodium and iron in the reduced state deposited on a support of alumina impregnated with a promoter amount of a heterocyclic amine at reaction conditions correlated so as to favor the formation of a substantial proportion of ethanol.

BACKGROUND OF THE INVENTION

This invention concerns the selective preparation of ethanol frommethanol and synthesis gas. More particularly, the invention concernsthe reaction of methanol and synthesis gas under heterogenous reactionconditions in the presence of a catalyst of rhodium and iron on analumina support containing a promoter amount of a heterocyclic amine toproduce ethanol.

The reaction of methanol with hydrogen and carbon monoxide to produceethanol and other oxygen-containing organic compounds is known anddisclosed in the prior art. For example, U.S. Pat. No. 4,133,966entitled SELECTIVE FORMATION OF ETHANOL FROM METHANOL, HYDROGEN ANDCARBON MONOXIDE discloses a process for the selective formation ofethanol which comprises contacting methanol, hydrogen and carbonmonoxide with a catalyst system comprising cobalt acetylacetonate, atertiary organo Group V A compound of the Periodic Table, a firstpromoter comprising an iodine compound and a second promoter compoundcomprising a ruthenium compound.

U.S. Pat. No. 3,285,948 entitled HALIDES OF RUTHENIUM AND OSMIUM INCONJUNCTION WITH COBALT AND IODINE IN THE PRODUCTION OF ETHANOL FROMMETHANOL, issued to Butter on Nov. 15, 1966, teaches a method forproducing alcohols in which any source of cobalt soluble in the reactionmedium which will yield a cobalt carbonyl or hydrogen cobalt carbonylunder the reaction conditions can be used. In addition, an iodinepromoter is employed, for example, I₂, or alkali metal iodines. Asecondary promoter is also employed, i.e., ruthenium halide or osmiumhalide. High selectivity is described as better when the secondarypromoter is used in combination with the primary promoter and otherreactants.

U.S. Pat. No. 4,013,700, entitled CATALYTIC PROCESS FOR POLYHYDRICALCOHOLS AND DERIVATIVES, issued to Cawse on Mar. 22, 1977, discloses aprocess for the preparation of polyhydric alcohols, their ether andester derivatives, and oligomers of such alcohols. In particular, thesealcohols and their derivatives are produced by reacting the oxides ofcarbon and hydrogen in the presence of a quaternary phosphonium cationand a rhodium carbonyl complex at elevated temperature and pressure.

Another process is set forth in U.S. Pat. No. 3,248,432, entitledPROCESS FOR THE PRODUCTION OF ETHYL ALCOHOL, issued to Riley et al onApr. 26, 1966, which relates to a process for the production of ethylalcohol by the interaction of methanol, carbon monoxide and hydrogen atelevated temperature and pressure in the presence of a cobalt catalystand an iodine promoter. Examples of suitable cobalt sources aredescribed as any water-soluble source of cobalt, for example, the cobaltcarbonyls, the lower salts of alkanoate cobalt, such as cobalt acetate,cobalt formate, cobalt propionate, and the like.

U.S. Pat. No. 2,623,906, entitled PREPARATION OF ORGANICHYDROXY-CONTAINING COMPOUNDS BY REACTING ALCOHOLS WITH CARBON MONOXIDEAND HYDROGEN, issued to Greshaw on June 16, 1948, relates to a procedurefor synthesizing mono and poly functional oxygen-containing organiccompounds by the reaction of alcohols, carbon monoxide and hydrogen.Catalysts described as suitable for use include various cobaltcompounds, for example, cobalt carbonyl, cobalt carbonyl hydride,metallic cobalt, and organic and inorganic cobalt salts.

Dutch Pat. No. 760,6138 entitled PROCESS FOR THE FORMATION OF ETHANOLFROM METHANOL AND SYNTHESIS GAS, issued to Shell International Researchon June 8, 1976, relates to a process for producing alcohols whichutilizes any soluble cobalt source which can generate a cobalt carbonylor hydrocarbonyl by reaction with the synthesis gas. For example,sources of cobalt suitable for use are cobalt iodide or cobalt metalfrom which ions can be generated in situ. Organic salts of cobalt suchas cobalt acetate, formate, or propionate are described as especiallygood sources, an iodide or bromide promoter is also utilized. Inaddition, the use of a tertiary phosphine is described as affordingimproved selectivity to the formation of alcohols.

U.S. application Ser. No. 437,141 filed Jan. 28, 1974, now abandoned,discloses a process for manufacturing acetic acid, its lower alkylesters, ethanol and lower alkyl aldehydes by contacting a reactionmixture of an oxide of carbon and hydrogen with a solid metal catalystfrom the group of rhodium, ruthenium, cobalt, osmium, iridium andplatinum. In one embodiment disclosed therein, methanol is co-fed withhydrogen and carbon monoxide over a supported rhodium catalyst with thereported result that productivities of the process were improved withthe addition of methanol to the fed gas.

U.S. application Ser. No. 541,660 filed Jan. 16, 1975, now abandoned,discloses a process for the selective preparation of ethanol bycontinuously contacting a synthesis gas reaction mixture containinghydrogen and carbon monoxide with a catalyst of rhodium and irondispersed on a particulate support.

U.S. application Ser. No. 153,610 filed May 27, 1980, now U.S. Pat. No.4,309,314, entitled CATALYTIC PROCESS FOR THE SELECTIVE FORMATION OFETHANOL FROM METHANOL AND SYNTHESIS GAS discloses a process for makingethanol and methyl acetate by contacting methanol, hydrogen and carbonmonoxide with a catalyst of rhodium and iron deposited on a support ofalumina containing a minor amount of an alkaline metal.

So far as applicant is aware, however, no process is provided forselectively preparing ethanol by contacting a mixture of methanol,carbon monoxide and hydrogen with a heterogenous catalyst comprisingrhodium and iron supported on an alumina support containing aheterocyclic amine. Unexpectedly, applicant has discovered that largeamounts of ethanol can be produced by contacting such a gaseous reactionmixture with the catalyst composition disclosed herein.

SUMMARY OF THE INVENTION

Briefly, in accordance with the invention, a process is provided for thereaction of methanol, carbon monoxide and hydrogen to produce ethanol bypassing a mixture of methanol, carbon monoxide and hydrogen over a solidcatalyst of rhodium in combination with iron deposited on an aluminasupport impregnated with a heterocyclic amine, preferably pyridine,under suitable reaction conditions.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Thus, one embodiment of the present invention is a process forselectively producing ethanol which comprises reacting methanol withcarbon monoxide and hydrogen in the presence of a heterogenous catalystcomprising rhodium and iron in the reduced state deposited on a supportof alumina impregnated with a promoter amount of a heterocyclic amine atreaction conditions correlated so as to favor the formation of asubstantial proportion of ethanol.

The catalyst used in the practice of this invention is also believednovel and that its constituents differ from those of the prior art.Thus, another embodiment of the present invention is a catalyst forselectively converting methanol, carbon monoxide and hydrogen toethanol, said catalyst comprising rhodium and iron in the reduced statedeposited on a support of alumina impregnated with a promoter amount ofa heterocyclic amine.

PROCESS DISCUSSION

The reaction is conducted at more or less conventional reactiveconditions of temperature, pressure, gas composition, and space velocityso that conventional technology and equipment may be used. Overall, thereaction is conducted at reactive conditions of temperature, pressure,gas composition and space velocity which are correlated to achieveoptimal selectivity for ethanol. The reaction efficiency, orselectivity, to ethanol is invariably in excess of 40% and is oftenbetween 60% and 70% excluding carbon dioxide and dimethyl ether asproducts. Selectivity is defined herein as the percentage of carbonatoms converted from carbon monoxide and methanol to a specifiedcompound or compounds other than carbon dioxide.

The reaction is exothermic with the thermodynamic equilibra and thekinetic reaction rates being governed by the reaction temperature. Ingeneral, the temperature can range from about 225° C. to about 275° C. Apreferred temperature is about 250° C.

The reaction zone pressure is desirably within the range of about 50psig to about 250 psig, with a pressure of approximately 220 psig beingpreferred.

The ratio of hydrogen to carbon monoxide in the synthesis gas may varysomewhat. Normally, the mole ratio of hydrogen to carbon monoxide iswithin the range of about 2:1 to 1:2. Preferably, the mole ratio ofhydrogen to carbon monoxide is about 1:1. Methanol is added to thesynthesis gas prior to introducing the gaseous reactant mixture into thereaction zone. Typically, a mole ratio of methanol to carbon monoxide ofapproximately 1:1 is used in the practice of the present process.

Conversion is conveniently achieved by employing a high space velocitycorrelated with other reaction variables (e.g. temperature, pressure,gas composition, catalyst, etc.). Space velocities of from about 800 toabout 2000 gas hourly space velocities (volumes of reactant gas at 0° C.and 760 mm mercury pressure, per volume of catalyst per hour) aregenerally employed. A preferred gas hourly space velocity isapproximately 1200 GHSV.

THE CATALYST

The rhodium-iron-heterocyclic amine promoted catalyst of the presentinvention is rhodium provided in combination with iron on a suitablealumina support which has been impregnated with a heterocyclic amine.

Heterocyclic amines which are useful in the present process are thesix-membered aromatic heterocycles which include pyridine andsubstituted pyridines. The substituted pyridines may have one or moresubstituents selected from hydrocarbyl, halogen, hydroxy, carbonyl,cyano, and the like. Illustrative examples of such substituted pyridinesare 2-hydroxypyridine, 3-iodopyridine, 4-cyanopyridine,4-acetylpyridine, 4(diphenyldimethyl)pyridine,4,4'-trimethylenepyridine, isoquinoline, 2-ethyl-4-chloropyridine,2,6-dimethyl-4-phenyl-pyridine and the like. Pyridine, isoquinoline, andthe C₁ -C₆ alkyl substituted pyridines are preferred. These preferredalkyl substituted pyridines may be mono-, di-, or trialkyl substitutedpyridines. Examples of these preferred alkyl substituted pyridines are2-methylpyridine, 3,5-dimethylpyridine, 4-ethyl-3,5-dimethylpyridine,4-butylpyridine, 3,4-diethylpyridine, 2-cyclohexylpyridine,3-tert-butylpyridine, and the like. The alkyl substituted pyridineswhich have no substituent in the position ortho to the nitrogen atom inthe pyridine ring are more preferred. Pyridine is most preferred.Catalyst preparation is typically effected by depositing rhodium andiron onto a high surface area alumina support and then impregnating thesupport with the amine aforedescribed.

In general, suitable support materials may include alpha alumina, betaalumina, gamma or eta alumina, alumino-silicates and magnesiumsilicates. Gamma alumina is the preferred catalyst support.

The rhodium and iron may be deposited onto the base or support by any ofthe techniques commonly used for catalyst impregnation, as for example,impregnation from an organic or inorganic solution, precipitation, etc.Conveniently, a solution of a heat decomposable inorganic or organicrhodium compound and an iron compound is appropriately contacted withthe support material and the support is then dried and heated, thelatter advantageously under reducing conditions, to form a finelydispersed rhodium-iron containing catalyst. These materials may bedeposited concurrently or sequentially. Illustrative of water-solublecompounds are the chloride and nitrate salts of rhodium and iron. Inpreparing the catalyst composition, the support material is contactedwith just enough solution of rhodium and iron compounds to wet thesupport so that little or no excess solution is used. This technique,which insures that the desired concentration of rhodium and iron will beincorporated into the catalyst composition, is known in the art and isreferred to as the incipient wetness technique. After impregnating thesupport material, the catalyst is subjected to drying conditions tolower the water content of the resultant composition to the lowestpossible level. In a typical drying procedure, the impregnated supportis slowly heated from room temperature up to a temperature ofapproximately 100° C. and is maintained at this temperature for at leastone hour, preferably from 1 to 24 hours, until substantially all of thewater is removed from the composition. The dried composition is thenreduced with hydrogen. It has been found advantageous to reduce thecatalyst composition by contacting the composition in a reduction zonewith hydrogen at room temperature and then heating the catalystreduction zone slowly from room temperature up to a temperature of about300° C. to 400° C. Reduction is continued at this temperature forapproximately 1 to 24 hours, preferably 7 to 8 hours, until both therhodium and iron components are reduced to the zero valent state. It isnot critical that reduction of the dried catalyst composition beinitiated at room temperature. Alternatively, the dried catalyst can beplaced in the reduction zone immediately after drying and reduction cancommence at an elevated temperature, for example, 200° C., asillustrated in Example 1 below.

The alumina support onto which the rhodium and iron components of thecatalyst composition have been deposited is then impregnated with anaqueous solution of a heterocyclic amine, such as pyridine, using theincipient wetness technique, aforedescribed. Typically, the rhodium-ironcontaining support is contacted with 3-5 milliliters of a solution ofpyridine dissolved in distilled water in an amount sufficient to providefrom about 0.1 to about 10.0 percent by weight, and preferably fromabout 2.0 to about 6.0 percent by weight, of pyridine on the catalyst.Following adsorption of the amine on the support, the impregnatedsupport material is dried at room temperature for at least one hour, andpreferably for at least 16 to 24 hours, to remove water from thecomposition. After drying, the composition is then reduced with hydrogenby contacting the composition in a reduction zone with hydrogen andslowly heating the reduction zone from room temperature up toapproximately 300° C. The reduction zone is maintained at thistemperature for approximately 1 to 24 hours in order to effect reductionof the final composition.

It is preferred that the catalyst contain from about 1.0 to about 10.0weight percent rhodium and from about 1.0 to about 10.0 weight percentiron based on the total weight of the catalyst composition. The amountof amine in the composition should range from about 0.1 weight percentto about 10.0 weight percent based on the total weight of thecomposition. An especially effective catalyst composition has been foundto comprise approximately 3.3 percent by weight rhodium metal and 3.4percent by weight metallic iron on a gamma-alumina support impregnatedwith 4.2 percent by weight pyridine.

After the catalyst has been prepared, the bulk volume of the weighedcatalyst is determined and the sample is placed in a test reactor(described below). The quantity of catalyst charged to the reactor istypically about 2.0 to 3.0 grams.

TEST REACTOR

The reactor used in the practice of the present invention is a stainlesssteel tube of 0.305 in. internal diameter, 0.375 in. outside walldiameter with a wall thickness of 0.035 in. The length is 14 inches andthe reactor capacity is approximately 16.5 ml. The tube is packed with acatalyst prepared as described above supported on a glass wool support.Carbon monoxide and hydrogen are fed to the reactor in the desired moleratio from 1750 psig headers. Approximately 2.0 to 3.0 grams of catalystare placed in the reactor on the support. The reactor is thenpressurized with hydrogen and the flow of carbon monoxide and hydrogenis adjusted to achieve the desired composition. During pressurization ofthe reactor, the reactor temperature and pressure are adjusted toreaction conditions. At least 5 to 6 hours are usually allowed for thereactor to come to a steady state before beginning to measure actualtime of reaction. Methanol is then mixed with the carbon monoxide andhydrogen components of the gaseous reaction mixture in the desired moleratio and the composite mixture is fed into the reaction zone of thereactor. The reaction is allowed to proceed and samples of liquidproduct are collected periodically by collecting the product containinggas through a cold water condenser at approximately 225 psig and thentrapping the liquid product in a dry-ice acetone trap having a capacityof approximately 55 cc. The liquid product from the trap and thecondenser are then combined to obtain a single liquid sample which isanalyzed by gas chromatography. The non-condensable gases are meteredthrough a wet-test meter to determine the volume of gas, and gas samplesare collected to determine their composition.

The following example serves to provide specific illustrations of thepresent invention.

EXAMPLE 1

This example illustrates the promoter effect that a heterocyclic amine,such as pyridine, has on the production of ethanol from methanol andsynthesis gas.

A solution was prepared by dissolving 1.7384 grams of rhodiumtrichloride, RhCl₃.3H₂ O, (obtained commercially from Alfa Products, 152Andover Street, Danvers, Me. 01923) and 8.7320 grams of ferric nitrate,Fe(NO₃)₃.9H₂ O (obtained from the J. T. Baker Chemical Company,Phillipsburg, N.J. 08865) in distilled water to a final volume of 50milliliters. The solution was heated until lukewarm to dissolve all ofthe salts so that the solution appeared homogeneous. The resultantaqueous solution was used to impregnate 22.5 grams of gamma-alumina (1.2mm) obtained from Rhone-Poulenc Industries, Division Chimic Fine, 30340Usine, De Salindres by adding the solution to the gamma-alumina supportin a 250 milliliter suction flask. The support was submerged in thesolution over the weekend. The support and solution were then pouredinto a crystallizing dish and heated over a hot plate set on the "Low"position for about 5 hours. The impregnated support was then dried in anoven at 100° C. overnight. The composition was then placed in thetubular test reactor, aforedescribed, and reduced with hydrogen byflowing hydrogen over the composition for approximately 6 hours whileslowly increasing the temperature in the reduction zone from 200° C. toabout 400° C. The composition was then reduced overnight atapproximately 400° C. The resultant composition was a gamma-aluminasupported catalyst containing approximately 3.3 weight percent rhodiumand approximately 3.4 weight percent iron. This catalyst is referred tohereinafter as Catalyst A.

A second catalyst was prepared containing a promoter amount of pyridineby impregnating 3.05 grams of the catalyst prepared as described abovewith 0.127 grams of pyridine dissolved in 3 milliliters of distilledwater using the incipient wetness technique. This produced a catalystcomposition containing approximately 3.3 weight percent rhodium, 3.4weight percent iron and 4.2 weight percent pyridine. The compositecomposition was then dried at room temperature overnight. Followingthis, the composition was reduced in hydrogen at 300° C. forapproximately 7 hours. This catalyst is referred to hereinafter asCatalyst B.

The catalysts, prepared as described above, were used in the followingreactions to demonstrate the selectivity of the amine promoter forproducing ethanol from methanol, carbon monoxide and hydrogen. Thereactions were conducted in the tubular flow test reactor aforedescribedunder the conditions designated in the Table below. The mole ratio ofhydrogen to carbon monoxide in all reactions was approximately 1:1. Inthose reactions where methanol was co-fed as a reactant with hydrogenand carbon monoxide, the mole ratio of hydrogen to carbon monoxide tomethanol was approximately 1:1:1. The reaction temperature wasmaintained at approximately 250° C. for all runs and the reactionpressure was held constant at approximately 220 psig for all runs. Runs1 and 2 were separate runs. Runs 3-13 were continuous with productsamples taken and analyzed at the times indicated.

                                      TABLE 1                                     __________________________________________________________________________    EFFECT OF AMINE PROMOTER ON CATALYST SYSTEM                                   __________________________________________________________________________                   Catalyst A          Catalyst B                                 Run No.        1         2         3     4     5.sup.a                        __________________________________________________________________________    H.sub.2 /CO    1.0       1.0       1.0   1.0   1.0                            Temp °C.                                                                              250       250       250   250   250                            Pressure, psig 220       220       220   220   220                            CO, moles/hr   .134      .134      .134  .134  .134                           MeOH, moles/hr .176      .114      0     0     .125                           GHSV           1990      1710      1200  1200  1760                           Time (hrs) from start                                                                        2.2       2.8       15.8  44.8  46.9                           of reaction              7.3       6.5   6.3   10.8                           C Conv, %      5.7                                                            Product Distribution, C %                                                                          *         *                     *                        CO.sub.2       5.2       6.2       5.4   6.6   8.1                            CH.sub.4       9.8   27.8                                                                              11.9  32.7                                                                              36.2  32.2  8.6   17.3                     C.sub.2 --C.sub.5 HC                                                                         3.2   9.1 2.3   6.3 11.5  9.2   3.8   7.7                      Me.sub.2 O     59.7      57.4      .1    .1    42.2                           MeOH                               18.1  7.0                                  EtOH           14.1  40.2                                                                              14.9  40.9                                                                              16.9  34.4  31.1  62.7                     MeOAc          6.5   18.4                                                                              5.2   14.4                                                                              1.2   1.5   3.5   7.0                      other oxygenates                                                                             1.7   4.8 2.1   6.0 11.9  9.2   2.7   5.3                      Turnover No, umole/g-min                                                      CO.sub.2       5.01      6.09      2.57  3.02  12.3                           CH.sub.4       9.47      11.8      17.3  14.8  13.1                           C.sub.2 --C.sub.5 HC                                                                         1.09      .75       1.89  1.46  1.98                           Me.sub.2 O     29.0      28.4      .019  .021  32.1                           MeOH                               8.67  3.22                                 EtOH           6.86      7.36      4.05  7.94  23.7                           MeOAc          2.09      1.72      .20   .22   1.77                           other oxygenates                                                                             .13       .99       1.68  1.39  1.67                           H.sub.2 O      106       78.0      16.7  30.1  2.39                           __________________________________________________________________________                  Catalyst B                                                      Run No.       6       7       8    9       10.sup.b                                                                              11                         __________________________________________________________________________    H.sub.2 /CO   1.0     1.0     1.0  1.0     1.0     1.0                        Temp °C.                                                                             250     250     250  250     250     250                        Pressure, psig                                                                              220     220     220  220     220     220                        CO, moles/hr  .134    .134    .134 .134    .134    .134                       MeOH, moles/hr                                                                              .123    .129    0    .124    .115    0                          GHSV          1750    1780    1200 1750    1710    1200                       Time (hrs) from start                                                                       48.9    50.9    67.2 69.3    72.1    88.1                       of reaction           8.3     8.2  12.5    7.9     7.4                        C Conv, %     9.2                                                             Product Distribution, C %                                                                        *       *            *       *                             CO.sub.2      8.7  26.1                                                                             8.8     6.9  5.7     11.8    7.3                        CH.sub.4      10.2 11.6                                                                             10.2 27.2                                                                             33.6 6.7  11.4                                                                             9.7  25.3                                                                             32.9                       C.sub.2 --C.sub.5 HC                                                                        4.6     4.7  12.5                                                                             8.3  2.6  4.5                                                                              3.3  8.7                                                                              8.3                        Me.sub.2 O    52.2    53.7    .3   35.3    49.8    .2                         MeOH                          26.4                 12.8                       EtOH          18.9 48.3                                                                             16.2 43.2                                                                             18.2 39.7 67.3                                                                             18.3 47.5                                                                             30.2                       MeOAc         3.7  9.5                                                                              4.6  12.3                                                                             1.7  4.4  7.5                                                                              5.1  13.1                                                                             1.3                        other oxygenates                                                                            1.8  4.4                                                                              1.9  4.8                                                                              4.7  5.6  4.4                                                                              2.0  5.4                                                                              6.9                        Turnover No, umole/g-min                                                      CO.sub.2      11.1    10.5    4.10 9.98    12.6    3.94                       CH.sub.4      13.1    12.1    20.1 11.8    10.4    17.7                       C.sub.2 --C.sub.5 HC                                                                        1.98    1.88    1.74 1.57    1.25    1.53                       Me.sub.2 O    33.1    32.0    .10  30.9    26.7    .053                       MeOH                          15.8                 6.89                       EtOH          12.1    9.65    5.45 34.8    9.78    8.13                       MeOAc         1.59    1.84    .33  2.59    1.80    .24                        other oxygenates                                                                            .91     .82     .96  3.49    .88     1.29                       H.sub.2 O     1.28    1.06    22.6 1.95    76.7    32.9                       __________________________________________________________________________                              Run No.       12      13                            __________________________________________________________________________                              H.sub.2 /CO   1.0     1.0                                                     Temp °C.                                                                             250     250                                                     Pressure, psig                                                                              220     220                                                     CO, moles/hr  .134    .134                                                    MeOH, moles/hr                                                                              .120    .122                                                    GHSV          1740    1750                                                    Time (hrs) from start                                                                       90.6    92.9                                                    of reaction           8.1                                                     C Conv, %     11.2                                                            Product Distribution, C %                                                                        *                                                          CO.sub.2      6.0     8.1                                                     CH.sub.4      7.9  14.1                                                                             8.5  20.7                                               C.sub.2 --C.sub.5 HC                                                                        2.8  5.1                                                                              2.7  6.6                                                Me.sub.2 O    38.1    51.1                                                    MeOH                                                                          EtOH          38.0 68.0                                                                             22.7 55.4                                               MeOAc         4.0  7.1                                                                              5.3  13.0                                               other oxygenates                                                                            3.2  5.8                                                                              1.8  4.2                                                Turnover No, umole/min                                                        CO.sub.2      9.29    9.19                                                    CH.sub.4      12.3    9.60                                                    C.sub.2 --C.sub.5 HC                                                                        1.45    1.08                                                    Me.sub.2 O    29.7    29.0                                                    MeOH                                                                          EtOH          29.6    12.9                                                    MeOAc         2.06    2.01                                                    other oxygenates                                                                            1.93    .75                                                     H.sub.2 O     1.76    95.8                          __________________________________________________________________________     *Distribution excluding CO.sub.2 and Me.sub.2 O                               .sup.a Reduced with hydrogen at 250° C. prior to run                   .sup.b 1 weight percent pyridine in MeOH feed immediately following run 9

The data in Table 1 demonstrates the excellent results obtained whenemploying the heterocyclic amine promoter of the invention in comparisonwith the rhodium-iron catalyst containing no promoter. As shown, theamine promoter produced significantly greater yields of ethanol atcomparable reaction conditions. Ethanol yields with promoter varied fromapproximately 44% (Run No. 7) to 68% (Run No. 12) excluding carbondioxide and dimethyl ether as products. In several of the runs,specifically, Runs No. 5, 9 and 12 ethanol yields exceeded 60%. Thespecific activity of the catalyst is represented by a "turnover number"which is defined as the number of micromoles of product formed per gramof catalyst per minute. The ethanol turnover number ranged fromapproximately 9.6 μmoles/g.-min. (Run No. 7) to 34.8 μmoles/g.-min. (RunNo. 9) with the amine promoter catalyst. The ethanol turnover numberswithout the amine promoter never exceeded approximately 8 μmoles/g.-min.(Run No. 11).

We claim:
 1. A catalyst composition for selectively converting methanol,carbon monoxide and hydrogen to ethanol, said catalyst comprisingrhodium and iron in the reduced state deposited on a support of aluminaimpregnated with a promoter amount of a heterocyclic amine.
 2. Thecomposition of claim 1 wherein said catalyst contains from about 1.0 toabout 10.0 weight percent rhodium; from about 1.0 to about 10.0 weightpercent iron; and from about 0.1 to about 10.0 weight percentheterocyclic amine based on the total weight of the catalyst.
 3. Thecomposition of claim 2 wherein said heterocyclic amine is selected frompyridine, isoquinoline and substituted pyridines wherein thesubstituents are selected from C₁ -C₆ hydrocarbon alkyl.
 4. Thecomposition of claim 3 wherein said hetercyclic amine is pyridine. 5.The composition of claim 1 wherein said support is selected from alphaalumina, gamma alumina, and eta alumina.